Meters used on motorcycles include digital displays of, for example, running time, engine temperature and other information. Since the motorcycles may be of the trail-type for traversing rough terrain, the meters must be robust to withstand vibration and shock. The meters must also be well sealed to prevent penetration of fine dust and moisture into the meter. For convenience, the interior of the meter housing that includes the electronic and other components and that is intended to be protected from penetration of dust and moisture will be referred to as the meter compartment, or simply “compartment.”
In the past, the technique for sealing the meter compartment included a small, passive vent that enabled filtered air to pass into and out of compartment. Thus, the pathway between the compartment and ambient air is continuously open, and the filter is relied upon for preventing penetration of fine particles. The continuously open air pathway compensates for changes in ambient pressure by permitting air flow between the compartment to equalize pressure inside and outside of the meter. In such a design, it is important that the vent also prevents the passage of moisture into the compartment while allowing the pressure-equalizing air flow. To this end, porous hydrophobic material is often selected for use as vent's filter, which spans an opening or passage into the compartment. Such material is not, however, completely effective, and over time the continuously open venting approach will enable moisture to accumulate within the meter compartment, which leads to corrosion and other problems, including fogging of the meter display when the moisture condenses on it.
One prior solution to the forgoing problem is to place a package of desiccant material within the compartment, but this merely delays the problem for as long as it takes for the desiccant to saturate.
Completely sealing the compartment (that is, eliminating the continuously open vent) is not a practical option because large changes in ambient pressure, such as pressure drops occurring when meters are shipped by air or otherwise transported to high-elevations, can lead to failure of the compartment water seals and/or distortion of the display and other components.
The present invention is directed to a solution to the forgoing problem and provides, among other things, a way of compensating for the pressure changes affecting sealed compartments by eliminating the prior art, continuously open pathway between ambient air and the compartment interior, while occasionally and briefly opening the pathway to prevent damage from extreme pressure differences.
In one illustrative embodiment of the present disclosure, a seal for a housing with an interior portion is disclosed. The seal comprises an axially inner surface configured to face the interior portion of the meter housing and an axially outer surface configured to face away from the interior portion of the meter housing. At least one of the axially inner surface and the axially outer surface is configured to seal against an outer cover of the meter housing. The seal further comprises a diaphragm defined axially intermediate the axially inner surface and the axially outer surface and a fluid passageway defined through a portion of the diaphragm. The fluid passageway is configured to move between an open position and a closed position in response to a pressure differential between the interior portion of the housing and an exterior portion.
In a further illustrative embodiment of the present disclosure, meter housing comprises a plurality of walls generally enclosing an interior portion of the housing and a seal positioned at one of the plurality of walls. The seal comprises an axially inner surface facing the interior portion of the housing and an axially outer surface facing a portion of the housing. At least one of the axially inner surface and the axially outer surface is configured to seal against the portion of the housing to sealingly enclose the interior portion of the housing. The seal further comprises a diaphragm defined intermediate the axially inner surface and the axially outer surface. The diaphragm has a fluid passage configured to open in response to a pressure differential between a pressure in the interior portion of the housing and a pressure exterior of the housing.
In another illustrative embodiment of the present disclosure, a housing comprises a plurality of walls generally enclosing an interior portion of the housing, an outer cover configured to be positioned adjacent an opening in one of the plurality of walls, an electrical component supported within the interior portion of the housing, and a seal positioned at the opening in the one of the plurality of walls. The seal comprises an axially inner surface facing the electrical component supported within the housing and an axially outer surface facing the outer cover of the housing. At least one of the axially inner surface and the axially outer surface is configured to seal against the housing. The seal further comprises a diaphragm defined intermediate the axially inner surface and the axially outer surface. The diaphragm has a fluid passage configured to open in response to a pressure differential between a pressure in the interior portion of the housing and a pressure exterior of the housing.
Other advantages and features of the present invention will become clear upon study of the following portion of this specification and drawings.